1. Field of the Invention
The present invention is directed toward liquid filled artillery projectiles and, more particularly, as directed towards a stabilization technique and apparatus for spin-stabilizing such artillery projectiles by causing the liquid payload therein to rapidly spin up to the angular velocity of the projectile in which it is encased.
2. Description of the Prior Art
It is generally well known to those skilled in the art that liquid payloads can destabilize the motion of an artillery shell in which it is encased. See, for example, the article entitled: "Engineering Design Handbook-Liquid-Filled Projectile Design," Army Material Command Pamphlet No. 706-165, 1969.
In order to successfully design such liquid-filled projectiles to be as free as possible from such spin-related instabilities, complex mathematical theories have been advanced and numerous "ad-hoc" engineering tests have been conducted. These theories and tests have led to the conclusion that the flight instabilities occur in a large part as a result of an oscillatory non-sloshing motion of the liquid which occurs prior to the time the liquid attains the spin velocity of the shell casing in which it is housed.
One prior art "ad-hoc" approach to liquid payload artillery shell stabilization has been to modify the internal geometry of the payload cavity by, for example, inserting various types of barriers, sleeves, fins, and the like, it being realized that the behavior of the liquid is highly dependent upon the geometry of the payload cavity. One such approach is described, for example, in a report entitled: "Stabilization of a Liquid-Filled Shell by Inserting a Cylindrical Partition in the Liquid Cavity," by J. T. Frasier and W. P. D'Amico, Ballistic Research Laboratories Report No. 1492, August, 1970. In the latter configuration, it was found that the burster modification requirements were too severe for production in requiring, for example, stress free welds and the like, which were very difficult to attain and maintain.
Another ad-hoc approach to stabilizing a liquid-filled shell is illustrated by the 105 millimeter, M410, WP-T (White Phosphorus-Tetryl) cartridge which has a six-bladed impeller attached to a central burster, as described in TM9-1300-203, Artillery Ammunition, April, 1967. This approach, as well as attempts to fill the payload cavity with a low permeability "metal sponge" proved to be unsuccessful during testing, the metal sponge approach being rejected for requiring too much volume within the payload.